Moritoshi Kinoshita

Detection of Three Genetic Polymorphisms in the 5' ''-Flanking Region and Intron 1 of Human CYP1A2 in the Japanese Population

Interindividual variability of the activity of CYP1A2 may be expected to affect cancer susceptibility, since the enzyme is capable of activating several carcinogens. In the present study, we found three new polymorphisms in the 5′‐flanking region (CYP1A2/B) and intron 1 (CYP1A2/C and CYP1A2/D) of CYP1A2 in Japanese by using polymerase chain reaction‐single strand conformation polymorphism. We developed methods to detect these polymorphisms by polymerase chain reaction‐restriction fragment length polymorphism and performed a population study (159 subjects) to estimate the frequencies of the alleles. The frequencies of the CYP1A2/A (adenine), CYP1A2/B (thymine‐deleted), CYP1A2/C (guanine) and CYP1A2/D (adenine) variants were 21.1, 42.0, 8.2 and 61.3%, respectively. The results of family study supported the idea that these CYP1A2 genotypes are inherited with an autosomal codominant transmission.

A new deleted allele in the human cytochrome P450 2A6 (CYP2A6) gene found in individuals showing poor metabolic capacity to coumarin and (+)-cis-3,5-dimethyl-2-(3-pyridyl)thiazolidin-4-one hydrochloride (SM-12502).

The S-oxidation of (4)-cis-3,5-dimethyl-2-(3-pyridyl)thiazolidin-4-one hydrochloride (SM-12502) and the 7-hydroxylation of coumarin are primarily catalyzed by cytochrome P450 2A6 (CYP2A6). The activities of SM-12502 S-oxidase and coumarin 7-hydroxylase were investigated with liver microsomes from 20 human individuals. Liver microsomes from individual H16 showed the lowest activities of both enzymes. The expression of CYP2A6 protein was not detectable in liver microsomes from individuals H4, H5, H7, H8, H12 and H16. CYP2A6 mRNA was hardly detectable in the liver of the individual H16. A new SacI-restriction fragment length polymorphism showing the lack of a 2.6 kb fragment was found in two of forty genomic DNA preparations from individuals H16 and No. 594, using CYP2A6 cDNA as a probe. This deletional 2.6 kb fragment was isolated from a genomic library prepared from one individuals showing normal coumarin 7-hydroxylase activity and was sequenced. This fragment contained a CYP2A6 gene region from 319 bp upstream of a putative exon 6 to a SacI site in exon 9, indicating that this region was deleted in the two individuals in this study. We also demonstrated by polymerase chain reaction analysis that the exon 8 of CYP2A6 gene was deleted in individuals H16 and No. 594. These results indicate that the reduced activity of SM-12502 S-oxidase and no activity of coumarin 7-hydroxylase are caused by the lack of CYP2A6 mRNA and CYP2A6 protein caused by the CYP2A6 gene deletion.

A new mutation of the fukutin gene in a non‐Japanese patient

Fukuyama‐type congenital muscular dystrophy (FCMD), Walker–Warburg syndrome, and muscle‐eye‐brain disease are clinically similar autosomal recessive disorders characterized by congenital muscular dystrophy, cobblestone lissencephaly, and eye anomalies. FCMD is frequent in Japan, but no FCMD patient with confirmed fukutin gene mutations has been identified in a non‐Japanese population. Here, we describe a Turkish CMD patient with severe brain and eye anomalies. Sequence analysis of the patients DNA identified a homozygous 1bp insertion mutation in exon 5 of the fukutin gene. To our knowledge, this is the first case worldwide in which a fukutin mutation has been found outside the Japanese population. This report emphasizes the importance of considering fukutin mutations for diagnostic purposes outside of Japan. Ann Neurol 2003

Frequency of BRCA1 and BRCA2 germline mutations in Japanese breast cancer families.

The purpose of this investigation is to study the frequency of BRCA1 and BRCA2 germline mutations in Japanese breast cancer families. Mutation analysis of BRCA1 and BRCA2 by SSCP was conducted on the 113 breast cancer patients (probands) with at least 1 breast cancer (site‐specific breast cancer families, n = 101) or 1 ovarian cancer (breast/ovarian cancer families, n = 12) patient in their first‐degree relatives. Fifteen deleterious mutations (13.3%), including 8 nonsense and 7 frameshift mutations, were identified in BRCA1, and 21 deleterious mutations (18.6%), including 8 nonsense, 12 frameshift and 1 splice‐site mutations, were identified in BRCA2. In site‐specific breast cancer families, mutation frequency of BRCA1 or BRCA2 was high in families with 3 or more breast cancer patients (36%, 9/25), early onset (40 ≤ years old) breast cancer patients (38%, 19/50) or bilateral breast cancer patients (40%, 6/15). In breast/ovarian cancer families, mutations of BRCA1 (58.3%, n = 7), but not BRCA2 (0%, n = 0), were observed. BRCA1 codon 63 (TTA to TAA) nonsense mutation and BRCA2 frameshift mutation (5802 del AATT) were observed in 4 and 7 independent families, respectively. Haplotype analysis has suggested that carriers of each of these mutations have common ancestors. These results demonstrate that family profiles are important determinants of risk for carrying a BRCA1 or BRCA2 mutation and that cumulative frequency of BRCA1 and BRCA2 mutations in Japanese breast cancer families (31.9%) is within the range observed in Caucasian breast cancer families. Presence of Japanese founder mutations has also been suggested. Int. J. Cancer 91:83–88, 2001.

ras Mutations in Endocrine Tumors: Mutation Detection by Polymerase Chain Reaction-Single Strand Conformation Polymorphism

To elucidate the molecular basis for endocrine tumorigenesis, ras mutations in human endocrine tumors were analyzed using polymerase chain reaction‐single strand conformation polymorphism (PCR‐SSCP) analysis. Mutations of the H‐, K‐, N‐ras genes were examined in genomic DNAs from 169 successfully amplified primary endocrine tumors out of 189 samples. Four out of 24 thyroid follicular adenomas analyzed contained mutated N‐ras codon 61, and one contained the mutated H‐ras codon 61. One of the 19 pheochromocytomas revealed mutation of the H‐ras codon 13. No mutations of the ras gene were detected in pituitary adenomas, parathyroid tumors, thyroid cancers, endocrine pancreatic tumors, and adrenocortical tumors. Based on these findings we conclude that activation of the ras gene may play a role in the tumorigenesis of a limited number of thyroid follicular adenomas and pheochromocytomas, and that mutation of the ras gene is not frequent in other human endocrine tumors.

Quasispecies nature of hepatitis C virus and response to alpha interferon: significance as a predictor of direct response to interferon

BACKGROUND/AIMS We evaluated the significance of the quasispecies nature of HCV as a predictor of the response to alpha interferon therapy in patients with chronic hepatitis C. METHODS Natural alpha interferon was administered in 62 patients for 24 weeks (daily for 2 weeks, then three times weekly for 22 weeks) and factors were analyzed that could affect the response. HCV subtype, HCV RNA concentrations and the number of HCV quasispecies were evaluated before treatment. HCV RNA concentrations were measured by branched DNA probe assay. The number of HCV quasispecies was measured by fluorescence single-strand conformation polymorphism analysis. RESULTS The HCV RNA concentration (p < 0.0001), HCV subtype (p = 0.0076), and the number of HCV quasispecies (p = 0.0024) were significantly associated with a complete response. Multivariate analyses showed that the number of HCV quasispecies was an independent predictor of the disappearance of HCV RNA during the administration of alpha interferon, but did not predict a relapse after its completion. Pretreatment concentration of HCV RNA was the only factor that was related to a long-term disappearance of HCV RNA. CONCLUSIONS The number of HCV quasispecies was significantly related to the response to alpha interferon early in its administration. The pretreatment concentration of HCV RNA was mainly related to a relapse following completion of treatment.

Cognitive impairment in amyotrophic lateral sclerosis and its relation to motor disabilities

The performance of patients with amyotrophic lateral sclerosis (ALS) on selective neuropsychological tests was examined in regard to the applicability of such examinations to diagnosis. Eighteen patients with ALS, and 15 age‐and education‐matched controls were given a battery of tests designed to assess motor and intellectual functions. The ALS group displayed significantly lower scores on all tests than those in the control group. Correlation analyses on the several motor and neuropsychological results in ALS group revealed that there was a significant negative correlation between upper motor symptoms and mini‐mental state examination, as well as memory tests.

Thermolabile phenotype of carnitine palmitoyltransferase II variations as a predisposing factor for influenza‐associated encephalopathy

To assess the etiology of influenza‐associated encephalopathy (IAE), a surveillance effort was conducted during 2000–2003 in South‐West Japan. All fatal and handicapped patients except one (4/34 patients) exhibited a disorder of mitochondrial β‐oxidation evoked by the inactivated carnitine palmitoyltransferase II (CPT II) with transiently elevated serum acylcarnitine ratios (C16:0 + C18:1)/C2 > 0.09 during high‐grade fever. Analyses of genotypes and allele compositions of CPT II revealed a thermolabile phenotype of compound heterozygotes for [1055T > G/F352C] and [1102G > A/V368I], which shows a higher frequency in IAE patients than healthy volunteers (P < 0.025). The thermolabile phenotype of CPT II variations may be a principal genetic background of IAE in Japanese.

Analysis of a chronic myelogenous leukemia patient vaccinated with leukemic dendritic cells following autologous peripheral blood stem cell transplantation.

Dendritic cells (DCs) are believed to be the most potent antigen‐presenting cells and may be important in the induction of anti‐leukemia specific T cell responses. In this preliminary clinical study, a patient with chronic phase chronic myelogenous leukemia (CML) was vaccinated with autologous leukemic DCs following autologous peripheral blood stem cell transplantation (PBSCT). In an in vitro study, leukemic DCs were generated using granulocyte‐macrophage colony‐stimulating factor (GM‐CSF), tumor necrosis factor‐α, and interleukin‐4 from granulocyte colony‐stimulating factor (G‐CSF)‐mobilized PBSC fraction of this patient, and were found to be Phl+, and to possess the morphologic and phenotypic characteristics of mature DCs. These cells could also elicit antigen‐specific immune responses, including a vigorous cytotoxicity specific to CML cells. In the clinical experiment, we obtained evidence that infused leukemic DCs could induce T cell clones expressing the same T cell receptor usage as a cytotoxic T cell line, suggesting that the immune repertoire includes tumor‐reactive T cells. These cytotoxic T lymphocytes are activated in vivo. The vaccination of leukemic DC caused a decrease in the number of Phl+ cells in the peripheral blood and bone marrow. These results indicate that the activity is an immunologically mediated phenomenon and vaccination therapy with leukemic DC following autologous PBSCT may be effective in treating CML.

A new variant CYP2D6 allele (CYP2D6*21) with a single base insertion in exon 5 in a Japanese population associated with a poor metabolizer phenotype.

Two poor metabolizer individuals of debrisoquine were identified among 215 healthy Japanese by a phenotyping test. Analysis of the CYP2D6 gene from one of two poor metabolizers, who was not homozygous for the previously described CYP2D6 variant alleles (CYP2D6*3, CYP2D6*4, CYP2D6*5 and CYP2D6*18), showed that this individual was heterozygous for a new allele, CYP2D6/C8 (CYP2D6*21). CYP2D6*21 had a single cytosine insertion at position 2661 in exon 5. This cytosine insertion generated a stop codon at the 17 bp downstream of this insertion site. A method to detect this allele was established with an allele specific-polymerase chain reaction. This method showed that another one of two poor metabolizers also possessed CYP2D6*21 allele heterozygously. In 318 healthy Japanese, five individuals carried this allele, heterozygously (0.81%, 5/636 chromosomes). Based on the present and our previous data, the poor metabolizer frequency in Japanese was estimated to be 0.39%, which accounted for approximately 45% of the individuals phenotyped as poor metabolizers by in-vivo tests.